1. Field of the Invention
The present invention relates to an automatic retractable antenna system, and more particularly, to a system for extending an automatic retractable antenna for combatting disturbances to the extending/retracting of a rod antenna.
2. Description of the Related Art
FIGS. 1 and 2 are perspective views of a conventional portable phone in an on-hook state and an off-hook state, respectively. The portable phone is a flip type.
The off-hook state refers to a speech mode state, and the on-hook state refers to a speech standby state. Referring to FIGS. 1 and 2, this portable phone includes a body 1000, a flip cover 2000, and a hinge (not shown) for mechanically connecting the body 1000 to the flip cover 2000.
The body 1000 has an upper casing frame 1010 and a lower casing frame 1020. An antenna device 1001 is installed on an upper end of the body 1000, and an ear piece 1002 is located on an upper portion of the upper casing frame 1010. Under the earpiece 1002 are disposed an LCD (Liquid Crystal Display) window 1003, a key pad 1004 including a plurality of keys, and a microphone 1005. The hinge is located at a lower portion 1006 which includes microphone 1005.
In accordance with the conventional portable phone, when the flip cover 2000 is opened, a speech mode is automatically set and a rod antenna 1001b is automatically extended. Conversely, when the flip cover 2000 is closed, a speech standby mode is automatically set and the rod antenna 1001b is automatically retracted.
FIG. 3 is a plan view of an automatic retractable antenna system inserted in an antenna housing 1001 a in the conventional portable phone. The conventional automatic retractable antenna system is installed in the lower casing frame 1020 by a fixing means including a fixing pin 452 and a bracket 420. Here, an elastic member 454, preferably constructed of rubber, is added to the fixing means to absorb vibrations generated when a motor 410 is driven. The rod antenna 1001b is moved by driving the motor 410 to rotate a pair of roller assemblies 430 and 440.
FIG. 4 is a perspective view of the conventional automatic retractable antenna system. The conventional automatic retractable antenna system includes motor 410, typically a small coreless type DC (Direct Current) motor, the pair of rollers 430 and 440 rotated by the motor 410, and the bracket 420 for fixing the rollers 430 and 440 to the motor 410. The motor 410 includes a motor shaft 411 which rotates clockwise or counterclockwise depending on the polarity of a power supply voltage received from a microprocessor. The outer circumferential surface of the motor shaft 411 is typically coated with rubber to maximize frictional and elastic forces.
The bracket 420 has a base 421 to be fixed to the motor 410 with respect to a rotating axis A1. A hole 422 is formed at the center of the base 421, for inserting the motor shaft 411 therein, and an engaging end 423 is bent downward from the outer circumferential surface of the base 421 and soldered to the motor 410. Thus, the bracket 420 is fixed to the motor 410. The bracket 420 also includes free ends 424 and 425 bent at a right angle to fix the roller assemblies 430 and 440. The free ends 424 and 425 have coaxial holes for inserting roller shafts 431a and 441a therein.
The roller assembly 430 has a disc shaped member 431 for contacting with the motor shaft 411 and roller 432 for contacting with the antenna system. Similarly, the roller assembly 440 has a disc shaped member 441 for contacting with the disc shaped member 431 of roller assembly 430 and a roller 442 for contacting with the antenna system. Similarly, the diameter of the rollers 432 and 442 is smaller than that of the disc shaped members 431 and 441. Thus, the motor shaft 411 rotates with respect to the axis A1, the roller assembly 430 with respect to an axis A2, and then the roller assembly 440 with respect to an axis A3 to effect a force transfer.
FIG. 5 is a plan view for describing the operation of the conventional automatic retractable antenna system. Referring to FIGS. 4 and 5, when the motor 410 is driven, the roller assembly 430 rotates in contact with the motor shaft 411 and the roller assembly 440 rotates in contact with the roller assembly 430. Then, the frictional force between the rod antenna 1001b and the outer circumferential surfaces of the rollers 432and 442 extends/retracts the rod antenna 1001b. The frictional force, since it is generated from the tight contact between the rollers 432 and 442, experiences little transfer loss.
When the motor shaft 411 rotates clockwise, the roller assembly 430 rotates counterclockwise in contact with the motor shaft 411, and the roller assembly 440 rotates clockwise in contact with the roller assembly 430.
Though the rollers 432 and 442 are formed of an elastic material such as rubber, they show limitations in their effectiveness of maximizing the frictional force with the rod antenna during extending/retracting the rod antenna. Especially, a slip phenomenon is frequently observed during the extending. and retracting operations. Furthermore, the extension/retraction of the rod antenna is not reliable because rod antennas typically do not have a constant diameter along its length. If a user inadvertently imposes an external impact on the rod antenna while extending it, the rod antenna is warped or malfunctions, deteriorating the antenna characteristics.
In view of the characteristics of a portable phone, it should be highly resistant against dropping or other impacts, and the rod antenna should be stably moved during extending/retracting. In addition, there is a need for extending/retracting the rod antenna by driving a motor with low power consumption and minimized frictional force.